Applications of Coherent X-Rays at the LCLS

Slide 1G. Grübel “Applications of Coherent X-rays at the LCLS” SLAC, October 17, 2008 1
Applications of Coherent X-Rays at the LCLS
Gerhard Grübel
Germany
G. Grübel “Applications of Coherent X-rays at the LCLS” SLAC, October 17, 2008 2
LCLS and coherence based techniques
Imaging techniques (CDI, FTH)
Recent developments and results
Conclusions
LCLS radiation (0.8 - 8 keV)
• ultrashort pulse duration 100 fs • extreme pulse intensities 1012-1013 ph
• coherent radiation
X-ray Photon Correlation Spectroscopy (XPCS)
LCLS Characteristics
Coherence based Imaging techniques
obey over-sampling condition or use reference beam (FTH)
Short pulse: snapshots (pump-probe) overcome damage limits
X-Ray Photon Correlation Spectroscopy (XPCS)
S(Q,t) dynamic structure factor
reciprocal space technique
(coherent) flux limited (τ >μs)
Short pulse: ns-fs timescale
Conclusions
Coherent Diffraction Imaging (CDI)
Reconstruction (phasing) of a speckle pattern: “oversampling” technique
gold dots on SiN membrane λ=17Å coherent beam at X1A reconstruction (0.1 μm diameter, 80 nm thick) (NSLS), 1.3.109 ph/s 10μm pinhole “oversampling” technique
24 μm x 24 μm pixel CCD
Miao, Charalambous, Kirz, Sayre, Nature, 400, July 1999
Reconstructed 3-D pattern (from 250 2-D projections). Phasing by “oversampling” technique.
3-D structure (2.5 Å resolution) of rubisco molecule.
(106 kDa)
Top view of a section (kz=0) of 3-D scattering pattern from 106 single molecules (of known relative orientation) each “exposed” by a single 10 fs XFEL pulse (λ=1.5Å, 0.1μm beamsize) containing 2.1012 photons.
J. Miao, K.O. Hodgson and D. Sayre, PNAS, 98, 6641 (2001)
An approach to three-dimensional structures of biomolecules by using single- molecule diffraction images: A simulation
“Single Molecule” Diffraction
Beam – Sample Interaction
I.K. Robinson, I.A. Vartaniants, G.J. Williams, M.A. Pfeifer, J.A. Pitney, Phys. Rev. Lett. 87, 195505 (2001) M.A. Pfeifer, G.J. Williams, I.K. Vartaniants, R. Harder and I.K. Robinson, Nature 442, 63 (2006)
CDI of (about 750 nm) Pb nanocrystals on Si substrate illuminated with 1.38Å coherent x-rays and CCD tuned to the Pb (111) reflec- tion (with 2 images separated by a 0.01 deg. rotation of the sample shown below).
Density of crystals is regarded as a complex function with the real part being the electron density and the imaginary part representing the projection of the local deformation of the crystal onto the Q vector of the Bragg peak being measured.
Reconstructed electron density revealing (111) facets.
Reconstructed imaginary part revealing (in the center) a phase-shift corresponding to about 1.1/2π (111) lattice spacings or about 0.5Å
Deformation fields inside nanocrystals
Fourier Transform Holography
Random magnetic (stripe) domains in a [Co(4)Pt(7)]50 ML sample, illuminated together with a reference aperature (1.5 µm) at the Co LIII edge absorption edge with a 778 eV (1.59 nm) 20 µm coherent soft x-ray beam.
S. Eisebitt, J. Lüning, W.F. Schlotter, M. Lörgen, O. Hellwig, W.Eberhardt and J. Stöhr, NATURE, 432, 885 (2004)
Incident FEL pulse: 25 fs, 32 nm, 4 x 1014 W cm-2
(1012 ph/pulse)
Model structure in 20 nm SiN membrane
Speckle pattern recorded with a single (25 fs) pulse
Reconstructed image
Femtosecond Imaging
Measure multiple (overlapping) diffraction patterns (as sug- gested e.g. by Rodenburg et al. and known as ptychography) to provide overdetermination in the data followed by a reconstruction algorithm(s): Difference map (Elser), Ptychography (Rodenburg et al.,.), Wigner Deconvolution (Rodenburg, Chapman,..)
201x201 diffraction pattern (6.8 keV), 300 nm beam (≈100 nm steps with 300 nm beam), 50 ms exposure from a 30 μm diameter Fresnel zone plate with 70 nm outer zone width.
P. Thibault, M. Dierolf, A. Menzel, O. Bunk, C, David, F. Pfeiffer, Science, vol 321, 381 (2008)
High-Resolution Scanning X-ray Diffraction Miroscopy
L.M. Stadler, C. Gutt, T. Autenrieth, O. Leupold, S. Rehbein,Y. Chuskin and G. Grübel; Phys. Rev. Lett. 100, 245503 (2008)
Combine FTH and CDI: Au nanostructure (letter “P”) 200 nm structure width; 220 nm height and 5 x 175 nm Au reference dots on 50 nm Si3N4 illuminated with 8 keV (10x10 μm2) beam. Use Fourier Transform Hologram as input for the CDI hybrid-input algorithm. Find resolution of about 25 nm and retrieve height of object: 235 nm +/- 10%
Hard X-Ray Holographic Diffraction Imaging
Ultrafast single-shot diffraction imaging of nanoscale dynamics
A. Barty et al., nature photonics 2, 415 (2008)
Pump-probe experiment on nano-patterned (FIP- etched) Si3N4 membrane (Ir-coated) pumped with Nd:YLF 523 nm, 12.5 ps long 25 μJ pulses and probed with 10 fs 13.5 nm 20 μm FLASH pulses.
Correlation functions indicate sample disintegration with a speed of about 5000-6000 m/s
Ultrafast single-shot diffraction imaging of nanoscale dynamics
Summary: Imaging TechniquesSummary
impressive progress in solving the inversion problem
better understanding of the damage problem
much progress towards biological systems (particle injection systems, molecular orientation,..)
“new methods” emerge (ptychography, combination CDI+FTH, FTH+URA, ..)
considerable single shot experience (XUV)
ultimately achievable resolution for small systems still under discussion
FEL light in the hard X-ray regime is missing
Conclusions
first (X-ray) speckle in 1991 (X25)
XPCS critical dynamics in Fe3Al (1995)
1st g2(t) function: colloidal gold (1995)
multitude soft matter studies (colloids, polymers...)
non-equilibrium dynamics (1998)
surface dynamics (2001)
Diffuse (001) peak of Cu3Au M. Sutton, S.G.J. Mochrie, T. Greytak, S.E. Nagler, L.E. Berman, G.A. Held and G.B.
Stephenson, Nature 352, 608 (1991)
<I(Q,t) I(Q,t+τ)> g2(Q,t) =
f(Q,t): intermediate scattering function
single Q (point detector): fast 2-D multi-Q (CCD detector): slow
Dynamics of complex fluids
f(Q,t) = exp (-Γt)
Γ(Q) = D(Q) Q2
D(Q) D0=kBT/6πηRH
silica (R=2610Å) in glycerol; T= 259 K; η=56 Pas
A. Robert J.Appl.Cryst.40,s34(2007)
Dynamics of complex fluids
PS-PI (R=23.7 nm) micelles in PS matrix at T 293 K (top) and 393 K (bottom)
The most likely density fluctuations decay the slowest
(deGennes narrowing)
Mochrie, Mayes, Sandy, Sutton, Brauer, Stephenson, Abernathy, Grübel, Phys. Rev. Lett. 78, 1275 (1997)
Phase – separating Glass
quench
Non-equilibrium Dynamics Malik, Sandy, Lurio, Stephenson, Mochrie, McNulty, Sutton, PRL 81, 5832 (1998)
Two time correlation function
[<I2(t1)> - <I(t1)>2]1/2 [<I2(t2)> - <I(t1)>2]1/2
Δt = t1-t2 t = (t1 +t2)/2
Fluctuations τ = τ ( q,t )
x
Two time correlation function
τ(q,t) ~ 1/q t 2/3
Surface dynamics
Γ(Q) = c Q c = γ(T)/2η(T)}
Seydel, Madsen, Tolan, Grübel, Press, Phys. Rev. B 63, 073409 (2001)
Particle Dynamics in Polymer-Metal Nanocomposite Thin Films
S. Narayanan, D.R. Lee, A. Hagman, X. Li and J. Wang, Phys. Rev. Lett. 98, 185506 (2007)
Au nanoparticles (0.9nm) on polystyrene (PS; RG=5-10nm) on Pd (Cr) Si substrate. RAU < RG probe individuality of polymer.
Increase intensity by wave-guiding effects
Entangled polymer [120, 65 kg/mol]:
Relaxation time ~ qR -1 (-0.9) drift mechanism
ß ≈> 1 aging, jamming
Relaxation time ~ qR -1.6 particles move
faster, governed by ß < 1 hydrodynamic
interactions
Antiferromagnetic domain fluctuations
Slow component indicative of thermally activated domain wall dynamics at high T and T independent switching (tunneling) at low T.
Shpyrko, Isaacs, Logan, Feng, Aeppli, Jaramillo, Kim, Rosenbaum, Zschack, Sprung, Narayanan, Sandy, Nature, 447, 68 (2007)
Chromium supports a SDW (including domain walls). The SDW is accompanied by a CDW.
Autocorrelation function of the [200] Bragg peak and the CDW superlattice peaks [2-2δ,0,0].
Summary: Imaging TechniquesSummary
steady progress since the 1991 paper
many applications from many different fields (soft matter, hard matter, surfaces and interfaces) indicating that XPCS has achieved quite some maturity
accessible dynamics mostly slow (τ > μs) and at moderate Q
limited by fast 2-d detectors but ultimately by coherent flux
fast (ns-fs) and(or) large Q dynamics only at a FEL source
need XCS beamline asap
SR based XPCS data
1-D
Summary: Imaging Techniques
Questions:
How to do (fast) dynamics experiments at a 120 Hz machine?
Is there enough intensity to (single-shot) image e.g. a magnetic system?
Can two subsequently recorded (speckle) pattern be compared?
XPCS at LCLS: movie mode
Movie mode allows access to slow dynamics: f << 1/ΔT = 120 Hz
Delay Line: 1ps <Δt <10ns (1ns 300 mm)
Delay-Line Mode
Delay-Line mode allows access to fast (fs-ns) dynamics
talk Roseker
X-ray delay-Line
available via DESY-SLAC MoU
Summary: Imaging Techniques
Questions:
How to do (fast) dynamics experiments at a 120 Hz machine?
Is there enough intensity to (single-shot) image e.g. a magnetic system?
Can two subsequently recorded (speckle) pattern be compared?
FLASH – the Free Electron Laser Facility Hamburg operating from 50 nm to 6.5 nm
Prototype experiments at Flash
average energy
per pulse
3rd harmonic 2.66nm ~ 72 nJ 1.0 * 109
5th harmonic 1.59nm ~ 3.5 nJ 2.8 * 107
wave- length
photons per pulse
pulse duration 10 fs at 8.0 nm 1 fs at 1.6 nm
Photon parameters at FLASH: Magnetism?
FLASH operates for λ > 6.5 nm
778 eV
Co LIII edge
Sample
CoPd multilayer , CoPt multilayer Hitachi (Hellwig), UHH (Oepen) 150 nm SiN membrane, 20 nm Pd base, 50 repeats of Co(1.2nm)/Pd(0.8nm), capped with 1.2 nm Pd providing out of plane magnetic moments
Actors
C. Gutt1, L.M. Stadler1, S. Streit-Nierobisch1, C. Günther2, R. Könnecke2, B. Pfau2, S. Eisebitt2, A.P. Mancuso1, J. Gulden1, B. Reime1, E. Weckert1, J. Feldhaus1, I.A. Vartaniants1, F. Staier3, A. Rosenhahn3, R. Barth3, M. Grunze3,M. Martins4, O. Hellwig5, H. Stillrich6, D. Stickler6, R. Frömter6, H.P. Oepen6, T. Nisius7, T. Wilhein7, K. Honkavaara1, B. Faatz1, R. Treusch1, S. Schreiber1, E. Saldin1, E. Schneidmiller1, M. Yurkov1 and G. Grübel1
1 DESY, Hamburg, Germany 2 BESSY, Berlin, Germany 3 Physikalische Chemie, Universität Heidelberg, Germany 4 Experimentelle Physik, Universität Hamburg, Germany 5 Angewandte Physik, Universität Hamburg, Germany 6 FH Koblenz, Remagen Germany
PRL (submitted)
Setup
PG 2 Beamline monochromator 200 lines per mm dispersive element : temporal broadening of pulse ca. 20-30 fs (ray-tracing) but transmission only 10-4 at 800 eV
Instrument: M. Martins, M. Wellhöfer, J.T. Hoeft, W. Wurth, J. Feldhaus, and R. Follath, Rev. Sci. Instrum. 77, 115108 (2006)
Experimental Setup
0.6
0.8
1
1.2
1.4
783.5 eV (off resoanance)
1000 s exposure (21 pulses x 5 Hz) Frame contains 6.7 x 104 photons
qmax=0.033 nm-1
778.1 eV (resonant Co L-edge)
Need x 105 for single shot (get 104 from beamline transmission and 104 from fundamental = x108)
Scattering close to the Co M edge
CoPt 23.5 nm (off resonance) 20 fs (single shot) 5 μJ (5x1011 ph/pulse)
Single bunch mode;
(fundamental)
Resonant Scattering at the Co M edge
CoPt 20.7 nm (on resonance) 20 fs (single shot) 5 μJ (5x1011 ph/pulse)
Single bunch mode;
E=59.9 eV (fundamental)
Resonant Scattering at the Co M edge
CoPt 20.7 nm (on resonance) 20 fs (single shot) 5 μJ (5x1011 ph/pulse)
Single bunch mode; 5 bunches/s
1-st bunch 2-nd bunch
CoPt 20.7 nm (on resonance) 20 fs (single shot) ≈5 μJ (5x1011 ph/pulse)
Single bunch mode;
0
5
10
15
20
25
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
FE L
pu ls
e en
er gy
[µ J]
Magnetic speckle pattern from two consecutive single shots low pulse energy
XPCS is feasible !!
• There is a route towards doing fast XPCS at a FEL machine. (delay-line mode)
• A prototype X-ray delay-line is tested and ready for use. • Standard (movie mode) XPCS is “straight forward”. • There is a series of very interesting experiments that are ready to go. • XCS beamline in 2011/2012 comes too late.
• The inversion problem seems to be under control. • Good understanding of the damage problem • Much progress toward biological systems
(particle injection systems, molecular orientation,..) • Considerable single shot experience (XUV) • Hard FEL X-rays are missing
• Detectors remain an issue.
• Information on the dynamics of a system can also be obtained by Imaging. The choice (XPCS vs. Imaging) depends on the problem. XPCS is less demanding since the inversion problem does not exist.
Summary
Layout
Coherent Diffraction Imaging (CDI)

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Applications of Coherent X-Rays at the LCLS